Proton Spin-Lattice Relaxation Rates in the Structural Analysis of Carbohydrate Molecules in Solution

Abstract

Publisher Summary This chapter focuses on proton spin–lattice relaxation rates in the structural analysis of carbohydrate molecules in solution. It gives an account of the simple theory related to spin-lattice relaxation-rates; cautions against the uncritical use of this simple theory for systems that are strongly coupled, or undergoing anisotropic reorientation, or both; introduces the pulse nuclear magnetic resonance (NMR) experiments that are used to measure spin–lattice relaxation-rates and to stress the precautions necessary for accurate measurements; discusses the types of experiments that reveal stereo-specific dependencies of spin–lattice relaxation-rates, along with concrete examples from the literature; and assesses the reliability of these experiments and their relative merits as to accuracy and technical simplicity. The proton spin-lattice relaxation-rate (R,) is a well established, NMR parameter for the structural, configurational, and conformational analysis of organic molecules in solution. However, its utility has received little attention in the field of carbohydrate chemistry and very few studies have been reported in which relaxation rates were used to extract qualitative or quantitative information, or both, about the geometry of carbohydrate molecules in solution. The chapter also provides details on the stereochemical implications of relaxation rates and explains the limitations and relative merits of relaxation methods.